On-highway and off-highway machines have engines, drivetrains, and other engine driven equipment, including pumps, which are susceptible to damage when operated at excessive speeds. Typically, the engine experiences a resistive load from the ground engaging elements, such as wheels or tracks, of the machine, and other final drive elements of the drivetrain of the machine. However, there may be times when the resistive load becomes a load that drives the engine. Such a condition may result, for example, from deceleration or traveling down a grade. More specifically, for example, this condition may occur when a machine is in gear and the weight of the load creates momentum sufficient to backload through the drivetrain and increase the engine speed. This increased engine speed may be above the normal speed range for the engine and may significantly decrease the life of the engine and attached components.
U.S. Pat. No. 3,999,386 to Crull et al. teaches an overspeed protection control for an engine driving at least one pump. The control includes hydro-mechanical valve means operable to cause an increase in pressure in a circuit supplied by the pump in response to an excessive engine speed. The increase in pressure results in an increase in load torque on the engine, thus reducing engine speed.
The present disclosure is directed to one or more of the problems set forth above.